The invention relates to a priority control device for at least two consumers having the features set forth in the preamble of claim 1.
It is known to divide the pressure medium or fluid amongst a priority consumer and a lower-ranking consumer in such a manner that both consumers are connected via a priority valve to the fluid line. The control piston of the priority control valve is subjected to the load pressure of the priority consumer and in the opposite direction to the pump pressure so that on actuating the control valve for the priority consumer the priority valve is moved so that the supply flow of fluid to the lower-ranking consumers is throttled and to the priority consumer is increased. The control piston of such priority valves is provided with three control edges.
It is also known (U.S. Pat. No. 2,892,311) to provide the priority control valve in the working line leading to the lower-ranking consumer. The control piston of this valve is subjected on the one hand to the working pressure tapped off at the priority load as control pressure and in the opposite sense to a pressure which is adjustable at an additional valve whose valve body is also subjected to the control pressure at the priority consumer. If on actuation of the priority consumer or load the control pressure rises the priority control valve is displaced and the flow of fluid to the lower-ranking consumer is throttled or shut off.
In particular in vehicles with hydraulic steering the steering must have priority in the supply with fluid, the supply of fluid to other hydraulic loads or consumers having to be throttled or shut off as soon as the steering valve is actuated.
The problem underlying the invention resides in constructing a priority control device, in particular for a hydraulic steering mechanism, in the simplest possible manner and so that it operates reliably.